A shoulder-held firearm is fitted with a butt to press the weapon against the shoulder and/or against the cheek of the shooter.
A disadvantage of this type of weapon is that, when firing, the shoulder of the shooter experiences a rather violent impact because of the recoil of the weapon due to the reaction forces from the gases formed by the ignition of the powder of the struck cartridge, whose bullet or shot is expelled from the barrel by the propulsion of these gases.
Another disadvantage linked to the recoil forces is that the shooter becomes a little unbalanced upon each shot fired, which is reflected in the fact that he must regain his balance each time in order to be in a stable position for the next shot.
This results in a lack of accuracy of the shot or a reduced rate of fire and a lack of comfort for the shooter.
In order to provide a certain comfort when firing, different shock-absorption systems are known to be used, such as a flexible protector rigidly affixed to the body of the butt and covering the rear part of the butt body, with such a protector being known by the name of recoil pad.
Despite the presence of a recoil pad, the forces that the shooter must take in his shoulder remain substantial.
The effect of the recoil may be also alleviated by personalising the recoil pad to the measurements of the user.
This solution is expensive and requires the intervention of an expert.
The weapon can only be adapted for the firing comfort of a single person.
The effect differs according to the clothes worn by the shooter, for example.
In general the recoil pad is not personalised for the shooter, especially if the weapon is used by several users.
The utility model DE 20.2007.012.495 discloses a butt which is provided at the rear with an assembly with a plurality of elements of which the position can be adapted to the shoulder of the shooter, the assembly being able to be rotated laterally around a shaft without clamping by means of a hook which is fixed to the shaft. The mechanism is very complex and adjustment to the shoulder is complex and difficult.
U.S. Pat. No. 1,468,354 discloses a butt in two parts of which the rear part, which is meant for being held against the shoulder of the shooter, is mounted an a swivel which allows to position the rear part in several positions with respect to the front part of the butt, the rear part being forced in a neutral position by means of springs positioned between the two parts of the butt. The rear part cannot be blocked in position on the front part.